The joining pars of a hinge through which the pin or rivet passes; a knuckle joint.

5. Shipbuilding

A convex portion of a vessel's figure where a sudden change of shape occurs, as in a canal boat, where a nearly vertical side joins a nearly flat bottom.

6.

A contrivance, usually of brass or iron, and furnished with points, worn to protect the hand, to add force to a blow, and to disfigure the person struck; as, brass knuckles; -- called also knuckle duster.

[Slang.]

Knuckle joint Mach., a hinge joint, in which a projection with an eye, on one piece, enters a jaw between two corresponding projections with eyes, on another piece, and is retained by a pin which passes through the eyes and forms the pivot. -- Knuckle of veal Cookery, the lower part of a leg of veal, from the line of the body to the knuckle.